Use the model viewer to determine what the actual name of the model is that you want to replace and the name of the model you want to replace it with. Use the mpq tool to then extract out the model(.m2) and skin (.blp) of the weapon you want to see (high warlord axe) now just rename the high warlord axe files using the names of the zulian stone axe files and place them in the proper directory. It's that easy.